Re: SubArray to ai record

[Andrew Johnson <anj@aps.anl.gov>]

Hi Amien,

On 03/18/2018 10:49 PM, Amien Crombie wrote:
> I'm using Base R3.14.12.3 running on a BeagleBone Black (os Ubuntu 14.04
> LTS) and please explain the easier way on Base 3.15 or >

For an IOC running a 3.15 or later release the CA server supports
server-side filters, one of which allows any CA client to request a
sub-set of an array field. Your ai records could thus be changed to look
like this instead without needing the subArray records at all:

record(ai,      "$(dev):mychann$(chan)")        {
    field(DTYP, "Soft Channel")
    field(INP,  "$(dev):xcur.[$(chan)] CP")
}

By including the CP flag these records will automatically process
whenever the waveform updates, so you don't have to forward-link to them.

Documentation on the array filter is available at
  https://epics.anl.gov/base/R3-15/5-docs/filters.html#Array-Filter-arr

HTH,

- Andrew


> On 2018/03/16 17:31, Andrew Johnson wrote:
>> Hi Amien,
>>
>> On 03/16/2018 09:19 AM, Amien Crombie wrote:
>>> I have a subarray record that looks like this:
>>>
>>> record(subArray,  "$(dev):$(channame)") {
>>>       field(SCAN,  ".1 second")
>>>       field(FTVL,  "FLOAT")
>>>       field(DTYP,  "Soft Channel")
>>>       field(INP,   "$(dev):xcur")  ## INP comes from a waveform of 8
>>> floats
>>>       field(NELM,  "1")
>>>       field(MALM,  "8")
>>>       field(INDX,  "$(chan)")   ## chan macro starts at 0
>>>       field(FLNK,  "$(dev):mychan$(INDX)")
>> What are you trying to achieve with the above FLNK value? Did you mean
>> to use $(chan) instead of $(INDX)? Do you have 8 copies of this record,
>> one each for chan=1, chan=2 etc?
>>
>>>   }
>>> record(ai,        "$(dev):mychann$(chan)")        {
>>>       field(DTYP,   "Soft Channel")
>>> }
>>>
>>> This is possibly not the right way to do it. Is there a better way?
>> I suspect you may be trying to extract each of the individual values
>> from the waveform into their own ai record, is that correct?
>>
>> Which version of EPICS Base are you using? There is an easier way than
>> creating 8 subArray records if you are using a 3.15 or later release of
>> Base.
>>
>> - Andrew
>>

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